Obama, fresh from efforts in Washington to secure bipartisan support for military intervention, said in Stockholm that the world had set “a red line” for Syria and it could not now remain silent in the face of the regime’s alleged strike on Damascus suburbs with chemical weapons.

White House officials have said Obama will hold meetings on the sidelines of G20 with French President Francois Hollande, the main foreign backer of a strike on Syria, as well as the leaders of China and Japan.

“The international community’s credibility is on the line and America and Congress credibility is on the line because we give lip service to the notion that these international norms are important,” he said.